Being overweight in old age does not always increase the risk of dementia, and sometimes even reduces it, scientists have concluded based on data from the large ARIC cohort study. The results of the work are published in the journal Neurology.
The study involved more than 5,000 people with an average age of around 75, who were followed for eight years. During that time, 20 percent of the participants developed dementia. It turned out that older people who were overweight and obese had a lower risk of the disease compared to their peers of normal weight. However, the key factor was not body weight itself, but its changes over time.
Those who lost weight between middle and old age were particularly vulnerable. They were significantly more likely to develop dementia, regardless of their initial body mass index. For example, among people of normal weight, the risk more than doubled if their weight decreased.
The authors emphasize: the results obtained explain the “obesity paradox” in late life. High weight in itself does not protect against dementia, and weight loss may be a marker of hidden pathological processes that accelerate brain aging. Therefore, it is worth assessing the risk not only by the current body mass index, but also by the dynamics of weight changes throughout life.
